Compact printer

ABSTRACT

An improved compact printer is provided which includes a rotary drive shaft having a notch therein, a print carrier carrying at least one print character on the periphery thereof rotatably mounted on the drive shaft, and driven means for rotating the print carrier through print selection and reset sequences. One end of the driven means is connected to the print carrier and the other end thereof is movably mounted on the driven shaft and accessible to the notch provided therein. Also provided are displaceable print means for imprinting a selected character carried on the print carrier on an imprint receiver and means for aligning a selected character carried on the print carrier in the print means path.

United States Patent Shimodaira May 20, 1975 [54] COMPACT PRINTERlS3rle3mnEr It I [75] Inventor: Tadayoshi Shimodaira, Matsumoto, 0 O a ea J an ap Primary Examiner-Edgar S. Burr [73] Assignee: Kabushiki KaishaSuwa Seikosha, Assistant E i Ed d M Coven Tokyo, Japan Attorney, Agent,or Firm-Blum Moscovitz Friedman 221 Filed: June 22, 1973 & Kapla 21 A 1.No.: 372 563 1 pp 57 ABSTRACT [30] Foreign Application Priority Data Animproved compact printer is provided which in- 2 J 47 61795 cludes arotary drive shaft having a notch therein, a June 22, 197 apan "47{09941 print carrier y g at least one print character on Nov. 2, 1972Japan the p p y thereof rotatably mounted on the drive shaft, and drivenmeans for rotating the print carrier [52] U.S.CCII. l0ll99,lOl/lll(i)zul 0ijgg through print Selection and reset Sequences one end[51] gl 99 of the driven means is connected to the print carrier [58] oearc 6 6 6 and the other end thereof is movably mounted on the drivenshaft and accessible to the notch provided therein. Also provided aredisplaceable print means [5 6] References cued for imprinting a selectedcharacter carried on the print UNITED STATES PATENTS carrier on animprint receiver and means for aligning 3,169,474 2/1965 Howard 101/1 10a selected character carried on the print carrier in the 3,307,6763/1967 Hickerson 101/110 X print means path 3,422,754 1/1969 Bakardjievet al.... 101/99 X 3,664,259 5/1972 Weinkle lOl/99 6 Claims, 8 DrawingFigures PATENI HAY 2 0 I975 SHEET 10F 3 PRIOR ART PATENTEUmzoms3,884,144

sun-:1 2 or 3 1 2/0? ART COMPACT PRINTER BACKGROUND OF THE INVENTIONThis invention relates to an improved compact printer of the typeutilized in electronic desk calculators and other numerical read outdevices. More particularly, this invention relates to novel means forprint selection and means for resetting the print carrier afterselection.

Prior printers include a plurality of concentric axially arranged printwheels which may be frictionally rotated for obtaining a selected printcharacter arrangement. The number of print wheels employed is determinedby the number of print columns desired. Print characters includingletters, numerals, functional signs and the like are conventionallyarranged in columnar fashion on the periphery of each print wheel.Usually, each print wheel of the plurality is rotatable for obtaining aselected array of characters. The oriented selected array is thereafterstriken with a print hammer, for instance a platen, to effect an imprintthereof on a paper receiver, for example, interposed therebetween.

Disadvantages of these prior printers include their large size andcomplex construction. Printers of this type have been used in the pastdespite their disadvantages because they perform at low noise levels.

Accordingly, the instant invention provides a simply constructed,compact printer which performs with a minimum of noise. Low noise levelperformance is a much sought after characteristic in view of recentnoise pollution studies here and abroad. Above all, the instantinvention provides a novel arrangement for aligning the print charactersand effecting an imprint.

SUMMARY OF THE INVENTION Generally speaking, in accordance with theinvention, an improved compact printer is provided which includes arotary drive shaft having a notch therein, one or more print carrierscarrying one or more print characters on the periphery thereof rotatablymounted on the drive shaft, and a discrete driven means for rotatingeach carrier through print selection and reset sequences. An end of thedriven means is connected to a corresponding print carrier, while theother end thereof is moveably mounted on the drive shaft accessible tothe notch provided therein. Also provided are displaceable print meansfor imprinting a selected character carried on a print carrier on animprint receiver and means for aligning a selected character carried ona print carrier in the print means path.

In practice, a plurality of print carriers coequal with the number ofprint columns desired are axially arranged on the rotary drive shaft anddriven thereby through the intermediate driven means which links eachdiscrete print carrier to the drive shaft. Lead rotation of the driveshaft causes a lag rotational sequence in the print carrier through thedriven means. The rotational sequence may be interrupted when a selectedcharacter carried on the print carrier is aligned in the print meanspath. After the selected character is striken by print means the driveshaft may be rotated in the reverse direction for resetting the printcarrier prior to a next successive selection sequence.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combinations of elements, and arrangement of parts which will beexemplified in the constructions hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of theinvention, reference is had to the following description taken inconnection with the accompanying drawings, in which:

FIGS. 1 and 4 are side elevational views of prior art embodiments;

FIG. 2 is a side elevational view of one compact printer embodimentconstructed in accordance with the invention;

FIG. 3 is an exploded perspective of a detail of the embodiment shown inFIG. 2;

FIG. 5 is a side elevational view of another compact printer embodimentconstructed in accordance with the invention;

FIG. 6 is a fragmentary sectional view of a detail of the embodimenttaken along the line AA in FIG. 5;

FIG. 7 is a schematic representation showing the manner of operation ofthe compact printer embodiment shown in FIG. 5; and

FIG. 8 is a cutaway view of yet another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown a prior art embodiment wherein a plurality of print wheels 1are axially arranged on a common shaft 3. Each print wheel is providedwith a concentric. axially arranged pinion 4. A peripheral segment of asector lever 5 is provided with a plurality of teeth 6 adapted to meshwith pinion 4, while a substantially adjacent segment thereof isprovided with a plurality of saw-blade teeth 7 which cooperate with aprint character selection lever 11 pivotably mounted for selectiveengagement and disengagement therewith.

Sector lever 5 is pivotably mounted on a shaft 8 and is tofque driveninto mesh with pinion 4 by a spring bias 10 having an end connectedthereto and a second fixed end. Oscillating rod 9 oscillates through aweighted arc in sector lever 5 for reciprocating sector lever 5 througha selected moment in cooperation with spring 10.

A spring 12 normally biases print character selection lever 11 forfrictionally engaging saw teeth 7 of sector lever 5. An electromagnet13, actuable by means not shown, stabilizes the position of selectionlever 11 for fixing respective positions of sector lever 5 and printwheel 1 for thereby arranging a selected print character 2 in a printposition. Aligned with the selected print character is a displaceableprint hammer 14 for striking an imprint of the selected character on aninterposed imprint receiver 15, for instance a paper of selected bond,through an ink ribbon 16.

In practice, as regulating rod 9 rotates clockwise through sector lever5, spring bias l0 cooperates therewith for rotationally advancing printwheel 1 until a selected print character 2 located thereon is arrangedin a print position. Simultaneous with display of the selected characterin the strike path of print hammer 14, means actuate electromagnet 13for stopping the clockwise advance of sector lever 5 and holding theselected character in print position for print hammer 14. After animprint strike, the electromagnet 13 deactivates, regulating rod 9swings counterclockwise for rotating sector level counterclockwise, andselection lever 11 bobs with the contour of saw teeth 7 travelingthereover.

Prior printers of the type described are defect prone because characterselection is gear determined. For instance. printed characters arecommonly of scattered height since the selected character is irregularlyoriented in the print display position, i.e. characters are notconstantly positioned in the hammer strike path, due to gear backlashand the like.

In FIG. 4 there is shown another prior printer embodiment wherein aplurality of print wheels 102 with peripherally arranged characters 103are axially arranged and rotatably mounted on shaft 101. A descriptionof one print wheel and its mode of operation will serve as a descriptionfor all. Fixedly mounted on shaft 101 for rotation therewith is springwasher 105 axially arranged and frictionally engaging print wheel 102for rotating print wheel 102. A radially located stop pin 107transversely mounted on print wheel 102 cooperates with stopper 108 forfixing the rest position of print wheel 102. A displaceable print hammereffects an imprint of a selectively displayed character on an interposedimprint receiver 110 through an ink ribbon 111. Spring biased, pivotablymounted print character selection lever 112 may be pivoted by the actionof an electromagnet 113 for engaging print wheel 102 along a groove 104thereof for thereby holding and displaying a selected print character103 in a print position. Spring 114 resets selection lever 112 to a restposition when electromagnet 113 is inactive.

In an operative mode, print wheel 102 rotates counterclockwise through acharacter selection sequence at an advance speed determined by theapplied frictional force of spring washer 105. The applied frictionalforce corresponds with the distortion of coacting spring washer 105 andthe gap distance between adjacent, axially arranged print wheels mountedon shaft 101. Dimensional variations among print wheels varies appliedfrictional forces and requires upward adjustment thereof withconcommitant excess power consumption. Spring washer 105 frictionallyengages print wheel 102 until the selection sequence ends or untilspring washer 105 rotates approximately 360 and while selection lever112 cooperates with groove 104 to display a selected character.Therefore, print wheel 102 carries a large load torque and a large powersource must be employed to provide the necessary startup energy requiredfor the selection sequence. Also, print wheel side walls are defaced andwear under the frictional force applied thereto and correspondingly, thefrictional force applied thereto varies.

After a print occurs, clockwise rotational sequence returns the printwheel to a rest position while in frictional engagement with springwasher 105. Disturbances in frictional force, print wheel pitch, highpower consumption, compensatory adjustments which may be required, andparts replacement render this type printer undesirable. Accordingly,embodiments constructed in accordance with the instant inventionovercome disadvantages of these prior printers.

Referring now to FIGS. 2 and 3, where there is shown a preferred printerembodiment constructed in accordance with the instant invention, arotary drive shaft is provided with a peripheral notch located in thethrust direction thereof. One or more axially arranged, concentric printcarriers, for instance a plurality of print wheels 22, are rotatablymounted on drive shaft 20. Each print wheel 22 is provided withperipherally arranged characters 23 and a coaxial, radially extendingratchet wheel 24 provided with a planar projection, stopper 25.Surrounding drive shaft 20 is sleeve 26 channeled to permit access tonotch 21 provided in drive shaft 20.

In an annular concentric recess provided in print carrier 22, a means27, for instanct a resilient spring member, is housed. An end of means27 is fixedly connected to print carrier 22 and the other end thereof isa free end which may ride and frictionally engage the notched surface ofdrive shaft 20. As drive shaft 20 rotates in a counterclockwisedirection, means 27 is driven thereby for rotating print carrier 22 in acorresponding counterclockwise direction. Alternatively, as drive shaft20 rotates in a clockwise direction, means 27 is frictionally driventhereby or driven thereby be cooperative notch 21 for rotating printcarrier 22 in a corresponding clockwise direction.

A selected print character 23 may be displayed in the strike path of aprint hammer 34 as print carrier 22 advances through a print characterselection sequence by coacting elements 28 to 32. A reciprocable lever28 pivotably mounted on a pin 30 is provided with a pawl end 29 normallypositioned for stopping the rotational advance of print carrier 22. Anend of reciprocable lever 28 is provided with a conductive face plateoperatively aligned with electromagnet 33. A reset spring 31 normallybiases reciprocable lever 28 against pivot stop member 32. Displaceableprint hammer 34 is positioned for striking a selected character forobtaining an imprint thereof on an imprint receiver 35 through an inkribbon 36.

As pattern carrier 22 is rotationally advanced through a characterselection sequence, drive shaft 20 is rotated counterclockwise forthereby rotating print carrier 22 in a counterclockwise directionthrough the frictional action of driven member 27 against notched driveshaft 20. When the selected character 23 is displayed in the printstrike path of print hammer 34 electromagnet 33 is actuated, by meansnot shown when the selected character is arranged in' the print positionopposite the print hammer 34. Simultaneously therewith the conductiveface plate of reciprocable lever 28 is attracted to electromagnet 33 andreciprocable lever 28 pivots for engaging pawl end 29 with teeth ofratchet 24 for thereby halting rotation of print carrier 22.Sequentially, after the advance of print carrier 22 is stopped bycooperating pawl end 29 and ratchet 24, print hammer 34 is actuated, bymeans not shown, for striking imprint receiver 35 and ink ribbon-36intovthe selected character 23. While the rotational advancesof patterncarrier 22 is halted, notched drive shaft 20 continues to rotatecounterclockwise and means 27 now unseated from drive shaft notch 21frictionally engages the drive shaft periphery. 'The frictional torqueimparted to means 27 is translated to a counterclockwise moment inpattern carrier 22 which drives ratchet 24 against pawl end 29 forthereby constantly maintaining the position of selected print carrier 23in the strike path of print hammer 34.

After the print strike of hammer 34 against selected character 23, driveshaft 20 is rotated in a clockwise direction and means 27 is driventhereby for rotating print carrier 22 in a corresponding clockwisedirection until stopper 25 strikes pawl 29 and print carrier 22 is resetto its initial position. After printer carrier 22 is reset, means 27frictionally engages the notched surface of drive shaft which continuesto rotate and means 27 again falls into notch 20 and sits therein. Inthis final position, elements of the printer are in a reset position andin position for a new selection sequence.

Referring to FIGS. 5 through 7, where there is shown another printerembodiment constructed in accordance with the instant invention, arotary drive shaft 120 is provided with a peripheral notch 121 locatedin the thrust direction thereof. One or more axially arranged,concentric print carriers, for instance a plurality of print wheels 122,are rotatably mounted on drive shaft 120. Each print wheel 122 isprovided with peripherally arranged characters 123 and a coaxially,radially extending ratchet wheel 124 provided with a planar projection,stopper 125. Surrounding drive shaft 120 is a sleeve 127 provided with achannel 126 for permitting access to notch 121 in drive shaft 120.

In an annular concentric recess 128 provided in print carrier 122, ameans 129, for instance a resilient spring member, is housed. An end ofmeans 129 carries an integral projection 141 freely carried in notch 121while the printer is at rest. Another end of means 129 is fixedlyconnected to the interior peripheral wall of ratchet 124. Means 129 iselastically deformable and the portion thereof carrying projection 14]projects toward the interior pattern carrier wall defining recess 128.

A selected print character 123 may be displayed in the strike path of aprint hammer 138 as print carrier 122 advances through a print characterselection sequence by coacting elements 130 to 137. A reciprocable lever130 pivotably mounted on a pin 131 is pro vided with an at rest positiondetermined by lever stop 132. A torsion coil spring 133 fixedlyconnected at one end to reciprocable lever 130 and at its other endfixedly connected to axle pin 134 mounted on the printer frame, notshown, determines stable rest and operating positions for reciprocablelever 130. Facing an electromagnet 135, actuable by means not shown, isa conductive face plate 136 mounted on reciprocable lever 130 oppositelyfrom electromagnet 135. A reset bar 137 is oscillatable between firstand second positions for resetting reciprocable lever 130 from anoperating position to a rest position.

At the conclusion of a character selection sequence,

a selected character 123 is arranged in the strike path of a printhammer 138 and print hammer 138 is actuated by means not shown forstriking imprint receiver 139 and ink ribbon 140 against the selectedcharacter 123 for securing an imprint thereof on imprint receiver 139.

Operatively, a coded print command is relayed to the printer by meansknown to the art and simultaneous therewith drive shaft 120 rotatesclockwise for thereby starting a character selection sequence. Patterncarrier 122 is advanced clockwise through a character selection sequenceby means 129 driven by drive shaft 120. instantaneously before selectedcharacter 123 is arranged in print position, a pulse-like voltage isapplied,

by conventional means, to electromagnet 135 for reciprocating lever 130in a counterclockwise direction for thereby halting the clockwiseadvance of print carrier 122. Lever 130 is provided with a pawl endengageable with teeth of ratchet 124 for halting the clockwise advanceof pattern carrier 122 and arranging selected character 123 in a stable,constant print position. Torsion coil spring 133 maintains lever 130 inposition in relative engagement with ratchet 124 during currentinterruptions through electromagnet 135.

Print carrier 122 may be advanced clockwise substantially 360 whereat anempty character position is located in the print hammer strike path.There may be occasions where a particular printout is of fewer columnsthan may be provided in terms of the printer capability.

During a clockwise character selection sequence projection 141 sits innotch 121 of drive shaft whereby means 129 is driven thereby forrotating print carrier 122. When the advance of print carrier 122 ishalted by the cooperative action of reciprocable lever 130 and ratchet124, drive shaft 120 continues to rotate elockwise and projection 141 ofmeans 129 releases from notch 121 therein and frictionally slides alongthe drive shaft surface.

After the printing stroke of print hammer 138, drive shaft 120directionally reverses to counterclockwise rotation, reset bar 137 isreciprocated for resetting lever 130 and the pawl end thereof disengagesfrom ratchet 124. Means 129 frictionally engagesthe rotating surface ofdrive shaft 120 and is frictionally driven thereby for rotating printcarrier 122 counterclockwise through a resetting sequence ending whenstopper engages the pawl end of lever 130. Drive shaft 120 continues torotate after print carrier 122 is reset until projection 141 of means129 again sits in notch 121 therein, thereby completing a print cycle.

According to this invention. frictional'drag exerted on a resilientspring member by a rotating drive shaft is employed for rotating a printcarrier. The frictional force which has to be developed for rotatingeach discrete print carrier is independent of the number of printcarriers axially arranged on the drive shaft and a constant frictionaltorque may be applied to each discrete print carrier without regardforthe number employed. It is found that large or small frictionaltorques may be selectively developed for rotating the print carrier byselectively carrying an end of the resilient spring member in the driveseat type notch provided in the drive shaft or by dragging that endthereof along the surface of the drive shaft. I

Since the resilient spring member may be housed in a narrow recessprovided in the print carrier and wound about the drive shaft, a smalldiameter print carrier may be provided therefore and the size of theunit may be reduced. It is critical however that the drive shaft be ofsufficient diameter that it will not deform under the pressure of theresilient spring member. In view thereof, it is also desirable that thecharacter print strike position be offset from the notch provided in thedrive shaft. This feature is best seen in FIG. 7, where it may beobserved that a print hammer strike of force F may be of sufficientimpact to exert an impact force against drive shaft 120. It is therefordesirable that the notched portion of the drive shaft be maintainedoutside the force field thereby developed. This may be accomplished byarranging that as first character 123-1 reaches the print positionoppositely print hammer 138, notch 121 rotates through an angle 0, to aposition 121' and by arranging that last character 123-14 rotatesthrough an angle 6 into print position while notch 121 is concomitantlypositioned at 121".

FIG. 5 shows yet another embodiment of the invention wherein theresilient spring member is differently arranged. Yet other arrangementswithin the scope of the invention may occur to the art skilled.

The resilient spring member employed herein may be fabricated of springsteel, plastic or any other material with the performancecharacteristics herein described. It is also contemplated that theresilient spring member may be integrally formed with the print carrier.

It will thus be seen that the objects and advantages set forth above,among those made apparent fromthe preceding description, are efficientlyattained and since certain changes may be made in the above constructionwithout departing from the spirit and scope of the invention, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

We claim:

1. A compact printer comprising a rotary drive shaft having an axiallyextending notch therein, said drive shaft being rotatable in first andsecond directions, at least one print carrier carrying at least oneprint character on the periphery thereof rotatably mounted on said driveshaft, said at least one print carrier being rotatable in firstandsecond directions corresponding to said rotary drive shaft, a resilientspring for rotating said at least one print carrier through printselection and reset sequences, respectively, corresponding to said firstand second directions thereof, said spring being driven by said notcheddrive shaft, said spring having a fixed end and a free end, said fixedend of said spring being fixedly connected to said at least one printcarrier, said free end of said spring having an elbow releasablyengageable in said drive shaft notch, said notch in said drive shaftproviding a drive seat for said free end of said spring for said shaftto thereby drive said spring, displaceable print means for imprinting aselected character carried on said at least one print carrier on animprint receiver, and means for selectively releasably locking theposition of said print carrier against the driving action of said driveshaft for thereby aligning a selected character carried on said at leastone print carrier in said print means path.

2. The compact printer of claim 1 wherein said looking means includes aratchet wheel connected to said at least one print carrier, areciprocable lever carrying a pawl at an end thereof engageable withteeth of said ratchet wheel and means for selectively reciprocating saidreciprocable lever at the conclusion of a print cycle, said drive shaftcontinuously rotating in said first direction until a print is effectedand said ratchet wheel and pawl end of said reciprocable lever beingcooperable for locking the position of said print carrier against thedriving action counter force thereof for stabilizing the position of adisplayed print character in the path of said displaceable print means.

3. The compact printer of claim 1 including an annular, concentricrecess provided in said at least one print carrier for housing saidspring, and a sleeve surrounding said drive shaft, said sleevepermitting access to said notch in said drive shaft.

4. The compact printer of claim 1 including means for driving said driveshaft in said first and second directions according to a selected printcommand, said spring and print carrier being correspondingly rotated insaid first and second directions in phase with the said drive means. g

5. The compact printer of claim 2 wherein said ratchet wheel rotatessynchronously with said print carrier, said pawl normally engaging saidratchet wheel, said ratchet wheel and said pawl being cooperable forpermitting said print carrier to rotate through a reset sequence after aselected print and including means for reciprocating said reciprocablelever for disengaging said pawl end thereof from said ratchet wheelduring a print cycle of said at least one print carrier.

6. The compact printer of claim 1 including means for resetting saidprint carrier at the conclusion of a print selection sequence.

1. A compact printer comprising a rotary drive shaft having an axiallyextending notch therein, said drive shaft being rotatable in first andsecond directions, at least one print carrier carrying at least oneprint character on the periphery thereof rotatably mounted on said driveshaft, said at least one print carrier being rotatable in first andsecond directions corresponding to said rotary drive shaft, a resilientspring for rotating said at least one print carrier through printselection and reset sequences, respectively, corresponding to said firstand second directions thereof, said spring being driven by said notcheddrive shaft, said spring having a fixed end and a free end, said fixedend of said spring being fixedly connected to said at least one printcarrier, said free end of said spring having an elbow releasablyengageable in said drivE shaft notch, said notch in said drive shaftproviding a drive seat for said free end of said spring for said shaftto thereby drive said spring, displaceable print means for imprinting aselected character carried on said at least one print carrier on animprint receiver, and means for selectively releasably locking theposition of said print carrier against the driving action of said driveshaft for thereby aligning a selected character carried on said at leastone print carrier in said print means path.
 2. The compact printer ofclaim 1 wherein said locking means includes a ratchet wheel connected tosaid at least one print carrier, a reciprocable lever carrying a pawl atan end thereof engageable with teeth of said ratchet wheel and means forselectively reciprocating said reciprocable lever at the conclusion of aprint cycle, said drive shaft continuously rotating in said firstdirection until a print is effected and said ratchet wheel and pawl endof said reciprocable lever being cooperable for locking the position ofsaid print carrier against the driving action counter force thereof forstabilizing the position of a displayed print character in the path ofsaid displaceable print means.
 3. The compact printer of claim 1including an annular, concentric recess provided in said at least oneprint carrier for housing said spring, and a sleeve surrounding saiddrive shaft, said sleeve permitting access to said notch in said driveshaft.
 4. The compact printer of claim 1 including means for drivingsaid drive shaft in said first and second directions according to aselected print command, said spring and print carrier beingcorrespondingly rotated in said first and second directions in phasewith the said drive means.
 5. The compact printer of claim 2 whereinsaid ratchet wheel rotates synchronously with said print carrier, saidpawl normally engaging said ratchet wheel, said ratchet wheel and saidpawl being cooperable for permitting said print carrier to rotatethrough a reset sequence after a selected print and including means forreciprocating said reciprocable lever for disengaging said pawl endthereof from said ratchet wheel during a print cycle of said at leastone print carrier.
 6. The compact printer of claim 1 including means forresetting said print carrier at the conclusion of a print selectionsequence.